Water Soluble Vitamins

Cobalamin Vitamin B12

Introduction Vitamin B12 includes a group of cobalt, containing compounds known as cobalamins. The major forms found in plasma and tissue include Methyl cobalamin Adenolylcobalmin and Hydroxycobalamin. All of these forms are biologically active.

Food sources Vitamin B12 occurs only in animal sources. The richest sources include Lamb and beef kidney Lamb and calf beef Liver and brain. Other good sources include Heart, egg yolk and variety of sea foods

Stability and solubility Stable to heat in aq.medium Only slightly soluble in water Little lost during cooking

Functions Vitamin B12 is required by all cells of the body, especially Gastro-intestinal tract Bone marrow and Nervous system. Within bone marrow, it is involved in conversion of ribose nucleotides into deoxyribose nucleotides

Functions (Contd.) An essential step in DNA synthesis. If DNA is not synthesized in enough quantities, large RBC’s (macrocytes) are released into the blood.

Absorption and Metabolism Vitamin B12 is absorbed through receptor sites in the ileum, mediated by intrinsic factor which is produced by glands in stomach. Vitamin is then transported across the intestinal cell and then into blood stream. Vitamin B12 is normally stored in liver for 3 to 5 years.

Recommended Dietary Allowances The RDA of 3.0 g of Vitamin B12 for adults allows for maintenance of adequate nutrition and substantial reserve body pool.

Effects of Deficiency Deficiency of Vitamin B12 is usually caused by defect in absorption rather than by dietary factors When intrinsic factor is not produced, Vit B12 is not absorbed.

Effects of Deficiency (Contd.) As a result, bone marrow cannot produced mature red blood cells and so releases the large, immature precursor (macrocytes) into blood stream instead. The symptoms of megalotblastic anemia include pallor, weight loss, anorexia, glossitis, sprue and in advanced stages, degeneration of spinal cord.

Toxic Effect No toxic effect in humans

Toxic Effects Generally considered to be nontoxic gastro-intestinal symptoms may be experienced by some individuals

Folic Acid (Folacin) Vitamin B10

Folacin is generic name for folic acid and related compounds. The chemical term for folacin or folic acid is pteroylglutamic acid.

STRUTURE Folic acid is a conjugated molecule consisting of a pteridine ring structure linked to para-aminobenzoic acid (PABA) that forms pteroic acid. Folic acid itself is then generated through the conjugation of glutamic acid residues to pteroic acid

Folic Acid positions 7 & 8 carry hydrogens,in Dihydrofolate (DHF) positions 5-8 carry hydrogens, in Tetrahydrofolate (THF)

All forms of folacin are equally utilized in the body More folacin is excreted in urine and feces than is accounted for in the diet, which indicates that this vitamin is also synthesized by intestinal flora Most of folacin is stored in liver Folic acid is converted to its biologically active form folinic acid in the liver

Recommended dietary allowance RDA for adults in 400 g of folacin daily

Deficiency Diseases Folate deficiency results in complications nearly identical to those of vitamin B12 deficiency. The most pronounced effect of folate deficiency on cellular processes is upon DNA synthesis. The result is megaloblastic anemia as for vitamin B12 deficiency.

Megaloblastic anemia

Deficiency Diseases The inability to synthesize DNA during erythrocyte maturation leads to abnormally large erythrocytes termed macrocytic anemia. Folate deficiencies are rare due to the adequate presence of folate in food. Poor dietary habits as those of chronic alcoholics can lead to folate deficiency.

Deficiency Diseases The predominant causes of folate deficiency in non-alcoholics are impaired absorption or metabolism or an increased demand for the vitamin. Certain drugs such as anticonvulsants and oral contraceptives can impair the absorption of folate. Anticonvulsants also increase the rate of folate metabolism.

Deficiency Diseases Folic acid appears to reduce the risk of stroke Low blood levels of folic acid are associated with increased risk of cancer. (Breast, pancreas and colon) Damage to DNA caused by folate deficiency may be the reason.

Prevention of Neural Tube Defect leading to spina bifida at the very early stage of pregnancy

INCREASED REQUIREMENT The predominant condition requiring an increase in the daily intake of folate is, pregnancy. pregnancy and infancy are both characterized by increased number of rapidly proliferating cells present in the blood. The need for folate will nearly double by the third trimester of pregnancy.

Possible Toxic Effect Risk from Folic acid Toxicity is very low. Tolerable upper intake level for adult is 1 mg/day. Upper intake level is 800 ug/day for pregnant and lactating women if less than 18 years of age. Supplemental level should not increase than the upper level to prevent folic acid from masking symptoms of Vitamin B-12

VITAMIN - C

Ascorbic Acid Ascorbic acid is commonly known as vitamin C Lactone Ring

Vitamin C exists in two forms, Ascorbic acid Most vitamin C is present in this form Dehydroascobic acid. Both are equally well utilized by humans

Functions This vitamin is essential for hydroxylation of amino acids Proline and Lysine to hydroxyproline and hydroxylysine respectively Important components of collagen , found in cartilage, bone, dentin and vascular epithelium. Vitamin C is important in wound healing

Functions 2. Other functions include: Synthesis of epinephrine and antiinflamatory steroid by adrenal gland White blood cell functions phagocytosis Folic acid metabolism –Redues folic acid to THFA and helps in maturation of RBCs

Functions Tryptophan metabolism to serotonin by hydroxylation Tyrosine metabolism to homogenestic acid by oxidation Iron metabolism facilitates the conversion of ferric to ferrous state which is preferentially absorbed

Functions Reconversion of methaemoglobin to hemoglobin Helps in the synthesis of bile acid from cholesterol Antioxidant,may prevents cancer Catract formation risk is reduced

Absorption and Metabolism Vitamin C is quickly absorbed form gastro-intestinal tract and distributed in various tissues of body Highest concentration are found in adrenal gland, with appreciable amounts in kidneys, spleen, liver, pancreas, thymus and pituitary Once the tissues are saturated, is excreted by the kidneys

Recommended Dietary Allowances 60 mg/day is required by both males and females Children have higher vitamin C requirement than do adults, on a weight basis

Food Sources Vitamin C is present in variety of fruits and vegetables Fresh, frozen or raw fruits and vegetables are best sources. citrus fruits, cabbage, spinach etc. Vitamin C is easily destroyed by prolonged cooking at high temperatures due to oxidation

Deficiency manifestations Deficiency of vitamin C results in faulty/ defective formation of collagenous intracellular substances.

Clinical Manifestations Joint pains Poor growth Anemia Increased susceptibility to infections and Poor wound healing

Advanced form of vitamin C deficiency results in scurvy Manifested clinically as Easy bruising, Bleeding gums and Hemorrhages

Toxic Effects Generally considered to be nontoxic gastro-intestinal symptoms may be experienced by some individuals